{"cve":"CVE-2026-64211","nvd":{"published":"2026-07-24T16:16:48.747","modified":"2026-08-11T17:24:10.577","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsrcu: Don't queue workqueue handlers to never-online CPUs\n\nWhile an srcu_struct structure is in the midst of switching from CPU-0\nto all-CPUs state, it can attempt to invoke callbacks for CPUs that\nhave never been online.  Worse yet, it can attempt in invoke callbacks\nfor CPUs that never will be online, even including imaginary CPUs not in\ncpu_possible_mask.  This can cause hangs on s390, which is not set up to\ndeal with workqueue handlers being scheduled on such CPUs.  This commit\ntherefore causes Tree SRCU to refrain from queueing workqueue handlers\non CPUs that have not yet (and might never) come online.\n\nBecause callbacks are not invoked on CPUs that have not been\nonline, it is an error to invoke call_srcu(), synchronize_srcu(), or\nsynchronize_srcu_expedited() on a CPU that is not yet fully online.\nHowever, it turns out to be less code to redirect the callbacks\nfrom too-early invocations of call_srcu() than to warn about such\ninvocations.  This commit therefore also redirects callbacks queued on\nnot-yet-fully-online CPUs to the boot CPU.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://git.kernel.org/stable/c/593889c401426004bd0ea0f6d4fcece728b03420","https://git.kernel.org/stable/c/a4153538fcd2361c4e0039eb103265492d26044e"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:46:40.600842820+00:00"},"epss":{"cve":"CVE-2026-64211","score":0.00143,"percentile":0.03617,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}